Justin Timberlake, Pharrell Williams, A$AP Rocky, and many other celebs attend the 2013 BET Awards; Beyonce kicks off her Mrs. Carter World Tour at Staples Center; Snoop, Kendrick Lamar, Miguel, Dr. Dre, J. Cole, and more perform together in concert for BET Experience; Tyga and Mike Epps compete in a celeb basketball game; Brooke Burke celebrates her Genlux Magazine cover; Maria Menounos and Wilmer Valderrama visit the Children's Hospital of Los Angeles—catch up on the weekend's top events in this edition of Last Night's Parties.